Re: use of aria-hidden to provide a text description not visible on the page.

aria-describedby pointing to hidden content results in the help content
(that is hidden) populating the MSAA accessible description.

If the label is hidden you have a problem as the IA2 accessibility API need
to point to the label through the labelled relationship. If it is hidden
there is no place to reference.

Rich

Rich Schwerdtfeger
CTO Accessibility Software Group



From:	Steven Faulkner <faulkner.steve@gmail.com>
To:	Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no>
Cc:	James Craig <jcraig@apple.com>, W3C WAI-XTECH
            <wai-xtech@w3.org>, HTML Accessibility Task Force
            <public-html-a11y@w3.org>
Date:	09/11/2010 08:01 AM
Subject:	Re: use of aria-hidden to provide a text description not
            visible on  the page.
Sent by:	public-html-a11y-request@w3.org



Hi Leif,
>Many ARIA supporting ATs doesn't actually seem to support this. :-(

i don't think this is a correct statement.
>Jaws11+Firefox3.6.9 is a quite common AT: It supports aria-labelledby.
>But fails to expose (to users) labels that have been hidden with CSS
>display:none or visibility:hidden.

worked for me for both aria-describedby and aria-labelledby referencing a
div hidden using CSS display:none


> And Jaws+IE7 at least isn't any better.
and so it shouldn't be since IE7 does not implement ARIA support.

regards
Stevef


On 11 September 2010 11:09, Leif Halvard Silli <
xn--mlform-iua@xn--mlform-iua.no> wrote:
  James Craig, Fri, 10 Sep 2010:
  >> "That's correct. The label of visible elements should still be
  >> exposed to accessibility APIs (as a computed string), even if the
  >> labeling element (that contained all or some of that string) is
  >> hidden."

  Many ARIA supporting ATs doesn't actually seem to support this. :-(
  See below.

  James Craig, Fri, 10 Sep 2010 12:25:01 -0700:
  > The spec recommends authors always SHOULD update the value of
  > aria-hidden, but in practice, when using visibility:hidden or
  > display:none it's rarely needed since all popular screen readers rely
  > on rendering engine support. Less common AT that is not supported by
  > a rendering engine (I think only FireVox, atm) relies on the DOM
  > being updated correctly, too.

  Aria-hidden="true" is probably most useful as a progressive enhancement
  feature for those AT that supports it. Example:

  Jaws11+Firefox3.6.9 is a quite common AT: It supports aria-labelledby.
  But fails to expose (to users) labels that have been hidden with CSS
  display:none or visibility:hidden. And Jaws+IE7 at least isn't any
  better.

  VoiceOver respects aria-hidden regardless of whether the element is
  actually hidden (via CSS), whereas Jaws+Firefox and NVDA+Firefox seems
  to fail to give any regard to aria-hidden whatsoever.

  Since common AT do not expose hidden labels, it might be best to, for
  maximum compatibility, to hide labels via other means, such as
  off-screen positioning. However, this could cause AT to present labels
  twice. But by setting such labels to aria-hidden="true", one can at
  least make sure that supporting AT, such as VoiceOver, does not read
  the labels twice.
  --
  leif halvard silli



--
with regards

Steve Faulkner
Technical Director - TPG Europe
Director - Web Accessibility Tools Consortium

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